syzbot


possible deadlock in smc_vlan_by_tcpsk

Status: upstream: reported on 2024/06/26 19:15
Subsystems: net s390
[Documentation on labels]
Reported-by: syzbot+c75d1de73d3b8b76272f@syzkaller.appspotmail.com
First crash: 20d, last: 20d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [net?] [s390?] possible deadlock in smc_vlan_by_tcpsk 0 (1) 2024/06/26 19:15

Sample crash report:
syz-executor.2[7759] is installing a program with bpf_probe_write_user helper that may corrupt user memory!
syz-executor.2[7759] is installing a program with bpf_probe_write_user helper that may corrupt user memory!
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc4-syzkaller-00869-g185d72112b95 #0 Not tainted
------------------------------------------------------
syz-executor.2/7759 is trying to acquire lock:
ffffffff8f5e6f48 (rtnl_mutex){+.+.}-{3:3}, at: smc_vlan_by_tcpsk+0x399/0x4e0 net/smc/smc_core.c:1853

but task is already holding lock:
ffff88801bed0258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1602 [inline]
ffff88801bed0258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xb7/0xde0 net/smc/af_smc.c:1650

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (sk_lock-AF_INET6){+.+.}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       lock_sock_nested+0x48/0x100 net/core/sock.c:3543
       do_ipv6_setsockopt+0xbf3/0x3630 net/ipv6/ipv6_sockglue.c:567
       ipv6_setsockopt+0x5c/0x1a0 net/ipv6/ipv6_sockglue.c:993
       do_sock_setsockopt+0x3af/0x720 net/socket.c:2312
       __sys_setsockopt+0x1ae/0x250 net/socket.c:2335
       __do_sys_setsockopt net/socket.c:2344 [inline]
       __se_sys_setsockopt net/socket.c:2341 [inline]
       __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2341
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (rtnl_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
       smc_vlan_by_tcpsk+0x399/0x4e0 net/smc/smc_core.c:1853
       __smc_connect+0x2a4/0x1890 net/smc/af_smc.c:1522
       smc_connect+0x868/0xde0 net/smc/af_smc.c:1702
       __sys_connect_file net/socket.c:2049 [inline]
       __sys_connect+0x2df/0x310 net/socket.c:2066
       __do_sys_connect net/socket.c:2076 [inline]
       __se_sys_connect net/socket.c:2073 [inline]
       __x64_sys_connect+0x7a/0x90 net/socket.c:2073
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sk_lock-AF_INET6);
                               lock(rtnl_mutex);
                               lock(sk_lock-AF_INET6);
  lock(rtnl_mutex);

 *** DEADLOCK ***

1 lock held by syz-executor.2/7759:
 #0: ffff88801bed0258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1602 [inline]
 #0: ffff88801bed0258 (sk_lock-AF_INET6){+.+.}-{0:0}, at: smc_connect+0xb7/0xde0 net/smc/af_smc.c:1650

stack backtrace:
CPU: 1 PID: 7759 Comm: syz-executor.2 Not tainted 6.10.0-rc4-syzkaller-00869-g185d72112b95 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
 smc_vlan_by_tcpsk+0x399/0x4e0 net/smc/smc_core.c:1853
 __smc_connect+0x2a4/0x1890 net/smc/af_smc.c:1522
 smc_connect+0x868/0xde0 net/smc/af_smc.c:1702
 __sys_connect_file net/socket.c:2049 [inline]
 __sys_connect+0x2df/0x310 net/socket.c:2066
 __do_sys_connect net/socket.c:2076 [inline]
 __se_sys_connect net/socket.c:2073 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2073
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0b3687d0a9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0b3764b0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f0b369b3f80 RCX: 00007f0b3687d0a9
RDX: 000000000000001c RSI: 00000000200000c0 RDI: 000000000000000a
RBP: 00007f0b368ec074 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f0b369b3f80 R15: 00007fff165a7738
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/22 19:11 net-next 185d72112b95 edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce possible deadlock in smc_vlan_by_tcpsk
* Struck through repros no longer work on HEAD.